I don't disagree, but my point is S.Korea is not just testing they are treating...if they were not treating presumably the mortality rates would increase. In other words whereas you suggest testing is proving the mortality rate is low, who many of those who tested positive received treatment? and further, got better because of treatment?
Testing is the key to treatment and minimizing mortality rates, other countries are failing on the testing, so it can be presumed they are also failing to treat (how can you treat when people aren't being tested).